Scaling, corrosion, precipitates, and material defects are some problems faced by the oil and gas industry when managing production well and pipeline assets. These problems lead to diminished production in wells, casing integrity failure, and pipeline integrity failure any of which may result in costly and complex remediation measures. As such, electromagnetic techniques are commonly used to monitor the condition of the production and casing tubulars, collars, filters, packers, and perforations. These techniques can measure eddy current signal data to obtain accurate measurements of tubular thickness and tubular corrosion.
This form of corrosion monitoring can be especially useful to prevent tubular integrity failures in mature wells or non-producing wells. For example, corrosion damage typically decreases the thickness of a casing tubular. One electromagnetic technique used for defect detection is the eddy current technique. In this technique, when a transmitter coil emits a primary electromagnetic field, or signal, eddy currents are produced in the tubulars. The eddy currents produce secondary fields or signals. Next, the secondary signals, sometimes called eddy current responses, are received by the receiver coil. When recorded and processed, the data resulting from the secondary signals can be employed to perform an evaluation of the tubulars.
The diameter of an innermost tubular of concentric tubulars limits the size of the tool that can be deployed to monitor the integrity of all the concentric tubulars. Moreover, effectively monitoring the outermost tubulars from the innermost tubular is difficult because the tool must sense through a number of tubular layers. Finally, the electromagnetic field used in the eddy current technique is applied without regard to the specific tubular configuration encountered downhole.
It should be understood, however, that the specific embodiments given in the drawings and detailed description thereto do not limit the disclosure. On the contrary, they provide the foundation for one of ordinary skill to discern the alternative forms, equivalents, and modifications that are encompassed together with one or more of the given embodiments in the scope of the appended claims.